Preparation Of "Three Defenses" Coatings On Aluminum Alloy And Mechanism Of Coatings

Aluminum alloy is a widely used material in the field of shipbuilding and aviation LY12CZ aluminum alloy is mainly used as the main structure of the aircraft. Meanwhile, because of their light weight and fast speed, the aluminum clippers has a large number of applications in short sea transport. Under natural conditions, it is easy to form a natural oxide film on the surface of aluminum alloy, but the film is porous and uneven, poor corrosion resistance, can not resist corrosion under harsh environmental conditions. Therefore, the aluminum alloy in the marine climate of the "three defenses" problem is still a serious problemIn order to improve the life of the aluminum alloy in marine climate. This topic is to prepare "three defenses", the so-called "three defenses" refers to the anti-moisture, anti-fog, anti-fungal. Therefore, prepare three coatings on the surface of aluminum alloy:the first layer of plate Ni-P coating; the second layer on the preparation for the thermo-chemical multiphase ceramic coating; the third layer of silicone epoxy resin coating by dipping method.Obtained by several experiments with the best ratio of the coating process:(1), Plate Ni-P:nickel sulfate 25g/L; hypophosphite 25g/L; lactic acid 30g/L; succinic acid lOg/L; malic acid 8g/L; sodium acetate lOg/L; pH:4.6～5.4; Temperature:85～90℃. Preparation of aluminum phosphate binder:13.6g aluminum hydroxide will dissolve in 13.8g water. Weighing 40ml 85% phosphoric acid concentration on the magnetic stirrer on a regular temperature, when the temperature rose to 60℃, slowly add the mixture to its full response. When the temperature rose to 100℃, heat 1.5h. Cooling the solution after the reaction, will get colorless and transparent solution of aluminum phosphate (2) Ceramic coating:MgO:Al2O3:SiO2:ZnO=2:6:1:1; aggregate:binder=1:2; 400℃fixed, heating rate of 2℃/min.60℃,100℃,200℃,300℃,400℃of the insulation 1h, after curing, with the furnace to cool to room temperature. (3) Organic coatings:silicone modified epoxy resin:xylene:dibutyl phthalate:polyamide=50:10:1:30; 2℃/min heating rate to 170℃,30min insulation. By SEM, metallographic analysis, XRD, such as salt spray on coatings, composition, performance analysis. The results showed that:the coating is uniform and compact, and a new phase formation, good resistance to salt corrosion and seawater corrosion, aluminum alloy can effectively improve the life in the marine climate...